JP2009139036A - Coating composition for heat exchanger hydrophilic post coat, and heat exchanger using it - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a coating composition for a heat exchanger hydrophilic post coat with superior hydrophilic persistence, pollution resistance, antibacterial activity, and economy, and with superior odor adsorption-fixing characteristics also. <P>SOLUTION: The coating composition comprises acrylic resin A, polyvinyl alcohol B, a polyphenol component C extracted from oolong tea, and a solvent D. A total weight of A and B is 1-50 wt.% with respect to a total weight of the coating composition, a ratio of A/B is 0.1-10, and a ratio of C/(A+B) is 0.0005-0.5. Furthermore, it can contain any one of a polyphenol component E, carbon black F, 2, 3, 5, 6-tetrachloro-4-methyl sulfonyl pyridine G, zinc bis [1, 2-dihydro-2-thioxopyridine-1-olate], or 2-(4-thiazolyl)-1H-benzimidazole within a certain range. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a coating for a hydrophilic postcoat of a heat exchanger. More specifically, the coating composition for a hydrophilic postcoat for a heat exchanger, which is excellent in hydrophilic durability, odor adsorption, stain resistance, antibacterial properties and economically, and The present invention relates to a heat exchanger using the same.

  Generally, a heat exchanger is made of aluminum and has a complicated structure in which fins for performing heat exchange are held between tubes at a narrow interval. For this reason, the surface of fins or the like is made hydrophilic to facilitate the discharge of water condensed during cooling. However, the surfaces of the above-mentioned hydrophilic fins and the like are repeatedly heated and cooled, and are exposed to harsh conditions in which condensed water, atmospheric dust and microorganisms are mixed and adhered. There was a problem that it was difficult to sustain.

  In addition, recent heat exchangers are required to have improved thermal efficiency and compactness in order to reduce weight, and a design that narrows the fin spacing as much as possible has been introduced. In the heat exchanger, moisture in the air adheres to the surface of the aluminum fin material as condensed water during the cooling operation. Since the surface of the metal material is generally poor in hydrophilicity, this condensed water exists on the surface of the fin material in a semicircular shape or a bridge shape between the fin materials. By preventing the flow of air between the fin materials by such condensed water, the ventilation resistance is increased and the heat exchange efficiency is remarkably lowered. Therefore, in order to improve the thermal efficiency of the heat exchanger, it is necessary to quickly remove the condensed water on the surface of the fin material.

  As a method for quickly eliminating condensed water on the surface of the fin material, (1) a method of forming a highly hydrophilic coating film on the surface of the aluminum fin material and allowing the condensed water to flow down as a thin water film, (2) an aluminum fin material Although a method of forming a water-repellent coating film on the surface and preventing condensed water from adhering to the surface is conceivable, the method (2) is extremely difficult at present. On the other hand, the method (1) is to form a coating film on the surface in order to obtain hydrophilicity, and such a hydrophilic coating film prevents the formation of condensed water droplets on the surface of the aluminum fin material, A water film formed on the surface of the aluminum fin material is held on the surface.

Various methods for forming hydrophilic coating films have been proposed and put into practical use. For example, a method of forming an alkali silicate anticorrosive coating on the surface of an aluminum material (Patent Document 1), a method of forming an aqueous paint coating (Patent Document 2), a low molecular organic compound having an alkali silicate and a carbonyl compound, and A method of forming a hydrophilic coating film by applying a composition containing a water-soluble organic polymer compound to an aluminum fin material (Patent Document 3) has been proposed.
Japanese Examined Patent Publication No. 53-48177 JP 55-164264 A JP-A-60-101156

  However, these hydrophilic coating films are poor in sustainability of hydrophilicity over time, and as a treatment method for performing post-coating, the film is not formed uniformly and a bridge is formed due to agglomerated water. It was difficult to apply as a post coat.

  Furthermore, in recent years, interest in the environment has been increasing, and odor components generated from the interior of cars and buildings are beginning to be regarded as problems. Therefore, in order to pursue comfort in such a living space, there is a demand for a heat exchanger that further purifies air while performing indoor air conditioning.

  However, it is difficult to effectively adsorb and remove odor components in the air by using the above-described hydrophilic post-coating coating composition, and there are no problems such as coating unevenness, repellency, sagging, etc. Until now, there has been no paint with excellent paint workability.

  The inventors of the present invention have made hydrophilic compositions that have excellent hydrophilicity, odor adsorption / fixing properties, antibacterial properties, economical efficiency, and excellent antifouling properties with respect to the coating compositions for hydrophilized postcoats of heat exchangers. As a result of diligent research on the development of a coating composition for a modified postcoat, a composition that exhibits excellent performance in any of these characteristics has been found, and the present invention has been completed. Thus, the object of the present invention is to provide a hydrophilic postcoat coating composition for heat exchangers that is excellent in hydrophilic durability, odor adsorption / fixing properties, antibacterial properties, economics and stain resistance on the surface of the heat exchanger, and An object of the present invention is to provide a heat exchanger using the composition.

The present invention relates to claim 1,
(A) an acrylic resin, (B) polyvinyl alcohol, (C) a polyphenol component extracted from oolong tea, (D) a solvent, and a hydrophilic coating composition comprising: (A) and (B) The total weight is 1 to 50% by mass with respect to the total amount of the coating composition, the ratio (A) / (B) is 0.1 to 10, and the ratio (C) / (A + B) is 0.00. A coating composition for a hydrophilic postcoat for a heat exchanger, characterized by being 0005 to 0.5.

Further, in claim 2, further comprising (E) a polyphenol component extracted from at least any of green tea and black tea, wherein the ratio of (E) / (A + B) is 0.0005 to 0.5. The coating composition for a hydrophilic postcoat for heat exchanger according to claim 1 is defined.

In claim 3, further,
(F) including carbon black having a primary particle size of 12 to 40 nm,
The ratio of (F) / (A + B) is 0.02-1. The hydrophilic post-coating coating composition for heat exchangers according to claim 1 or 2 is defined.

  In Claim 4, the carbon black surface is surface-treated with humic acid, and the coating composition for hydrophilized postcoat for heat exchanger according to claim 3 is defined.

In claim 5, further,
(G) 2,3,5,6-tetrachloro-4-methylsulfonylpyridine, zinc bis [1,2-dihydro-2-thioxopyridine-1-olate], 2- (4-thiazolyl) -1H- Including at least one of benzimidazole,
The ratio of (G) / [(A) + (B)] is 0.05 to 1. The coating composition for a hydrophilized postcoat for a heat exchanger according to claim 1 to 4 is defined. .

  And in Claim 6, the heat exchanger manufactured by paint-baking the coating composition of Claims 1-5 is prescribed | regulated.

  According to the present invention, the coating composition for hydrophilized postcoat that is excellent in long-term hydrophilicity, stain resistance, antibacterial property, economically on the surface of the material such as aluminum material and excellent in odor adsorption / fixing property. A heat exchanger manufactured using the product can exhibit performances excellent in hydrophilic durability, stain resistance, economy, and odor adsorption / fixing properties.

Acrylic resin The component (A) acrylic resin used in the present invention is a resin formed from an α, β monoethylenically unsaturated monomer and a monomer polymerizable thereto. For example, acrylic acid esters (methyl acrylate, ethyl acrylate, isopropyl acrylate, nbutyl acrylate, 2-ethylhexyl acrylate, decyl acrylate, isooctyl acrylate, 2-ethylbutyl acrylate, octyl acrylate, methoxy acrylate) Ethyl, ethoxyethyl acrylate, ethoxypropyl acrylate, etc.), methacrylic acid esters (methyl methacrylate, ethyl methacrylate, isopropyl methacrylate, butyl methacrylate, isobutyl methacrylate, n-hexyl methacrylate, lauryl methacrylate, Decyloctyl methacrylate, stearyl methacrylate, 2-methylhexyl methacrylate, 3-methoxybutyl methacrylate, etc.), acrylonitrile, methacrylonitrile, vinyl acetate, vinyl chloride , Vinyl ketones, vinyl toluene and styrene.

    Monomers that can be copolymerized therewith are styrene, α-methylstyrene, vinyltoluene, t-butylstyrene, ethylene, toluene, propylene, acrylamide, hydroxypropyl acrylate, 2-hydroxyethyl acrylate, methacrylic acid 2 Hydroxyethyl, hydroxypropyl methacrylate, N-methylolacrylamide, of course, acrylic acid, methacrylic acid, crotonic acid, itaconic acid, maleic acid, fumaric acid and the like can also be used.

  The polymerization degree of the acrylic resin is preferably about 50 to 40,000, more preferably about 100 to 20000.

Polyvinyl alcohol As the component (B) polyvinyl alcohol used in the present invention, those having a saponification degree of 90 mol% or more or those of a complete saponification type are preferably used. The average degree of polymerization of the polyvinyl alcohol resin is 500 to 2500, more preferably 1500 to 2500. When the saponification degree is less than 90 mol% or the average polymerization degree is less than 500, the hydrophilicity is poor or the adhesion is poor. On the other hand, when the average degree of polymerization is higher than 2500, the increase in viscosity becomes remarkable, causing a problem in paintability.

  In addition to the above-mentioned polyvinyl alcohol resin, for example, a small amount (for example, 5% by mass or less) of allyl glycidyl ether is copolymerized during polymerization of vinyl acetate, and a part of the hydroxyl group is substituted with an epoxy group. Or by copolymerizing a monomer having a carboxyl group such as crotonic acid, acrylic acid, maleic anhydride, itaconic acid, MMA (methyl methacrylate) during the polymerization of vinyl acetate. The introduced modified polyvinyl alcohol and the like are also included.

  One kind of the acrylic resin may be used, or two or more kinds of different kinds of acrylic resins may be used. Further, one kind of the polyvinyl alcohol resin may be used, or two or more kinds of different kinds of polyvinyl alcohol resins may be used. Further, an acrylic resin and a polyvinyl alcohol resin may be used together.

  As a blending ratio of the acrylic resin (A) and the polyvinyl alcohol (B), the ratio (A) / (B) needs to be 0.1 to 10, and preferably (A) / (B) is 1 to 7.5. When (A) / (B) is less than 0.1, since the acrylic resin component is small, water resistance is poor when a film is formed, and hydrophilic sustainability cannot be obtained. Moreover, when (A) / (B) is larger than 10, since the polyvinyl alcohol component is small, hydrophilicity cannot be ensured when a film is formed.

  Moreover, as content of the resin component in a coating composition, the total amount of both (A) and (B) needs to be 1-50 mass% with respect to all the coating compositions. When the amount is less than 1% by mass, hydrophilicity in the obtained heat exchanger becomes insufficient. When the amount exceeds 50% by mass, paintability to the heat exchanger, film thickness uniformity, dripping, and the like become problems.

Crosslinking agent It is good also as a crosslinkable resin of a three-dimensional arrangement | sequence by mixing a crosslinking agent in said acrylic resin and polyvinyl alcohol resin. A crosslinking agent is mix | blended as needed for the purpose of improving the water-soluble solubility of the film obtained. Examples of such a crosslinking agent include metal chelate compounds such as melamine resin, urea resin, phenol resin, polyepoxy compound, blocked polyisocyanate compound, and titanium chelate.

Oolong tea component The component (C) polyphenol component extracted from Oolong tea used in the present invention is not particularly limited as long as it has a component containing polyphenol extracted from Oolong tea. For example, when the oolong tea leaves and stems are heated from room temperature to a predetermined temperature, water, acidic aqueous solution, aqueous ethanol, ethanol, aqueous methanol, methanol, acetone, ethyl acetate, glycerin aqueous solution, etc. An extract extracted with a solvent or a mixed solvent thereof is used. In addition to using an extract obtained by removing the solvent from the extract, it can also be used as an extract obtained by extraction (consisting of an oolong tea component and an extract solvent) or as a concentrate of the extract. In particular, a method of adding room temperature water or an extraction liquid itself extracted with warm water to the coating composition for a hydrophilic postcoat is preferable from the viewpoint of adsorptivity of odor components.

  The polyphenol component extracted from oolong tea in the resin component is a component having a function of adsorbing odor components. The polyphenol component extracted from the oolong tea component needs to have a ratio of (C) / (A + B) in the range of 0.0005 to 0.5. If the polyphenol component extracted from oolong tea is less than 0.0005 with respect to the (A, B) resin component, it will be difficult to obtain adsorption / fixing properties of odor components, and if it exceeds 0.5, the desired hydrophilicity will be obtained. It will decline.

  Oolong tea components obtained by such extraction include catechins (catechin, gallocatechin, epicatechin, epigallocatechin, catechin gallate, epicatechin gallate, gallocatechin gallate, epigallocatechin gallate); tannins. In addition, flavonoids such as kaempferol, quercetin, myricetin; polyphenols such as GOD polyphenol; organic acids such as malonic acid, succinic acid, gallic acid; caffeine; amino acids; sugars; vitamins; ing.

  By including in the composition a polyphenol extracted from the oolong tea component such as the catechins, the adsorption / fixing property of the odor component is enhanced. Among these polyphenols, catechins (catechin, gallocatechin, epicatechin, epigallocatechin, catechin gallate, epicatechin gallate, gallocatechin gallate, epigallocatechin gallate) greatly contribute to the adsorptivity of odor components. In particular, a multimer in which these catechins are associated, preferably a catechin dimer and a trimer, effectively acts to increase the adsorptivity of formaldehyde. Since the catechin dimer and trimer are contained in a large amount in the polyphenol in the oolong tea component, the adsorptivity of the odor component can be ensured.

Green tea ingredients and black tea ingredients
The polyphenol component extracted from at least any of component (D) green tea and black tea used in the present invention is not particularly limited as long as it has a component containing polyphenol extracted from green tea and black tea.

As said manufacturing method, the method similar to the extraction method of said Oolong tea component is used.
The polyphenol component extracted from the green tea and black tea in the resin component is a component having a function of fixing the odor component. Polyphenol (D) extracted from green tea and black tea needs to have a ratio of (D) / (A + B) in the range of 0.0005 to 0.5. If the polyphenol component extracted from green tea and black tea is less than 0.0005 with respect to the (A, B) resin component, it becomes difficult to obtain fixability of the odor component, and if it exceeds 0.5, the desired hydrophilicity is obtained. It will decline.

Carbon black Carbon black (E) is added to improve the adsorptivity of odor components and the resistance to contamination. The carbon black used in the present invention can be produced by a known method, and the production method is not particularly limited. For example, the carbon black is produced by a channel method, a roller method, a furnace method, or the like. Further, as long as the characteristics of the carbon black in the present invention are met, the manufactured carbon black may be further subjected to further treatment such as a known oxidation reaction.

In the present invention, carbon black having a primary particle size of 12 to 40 nm is used. Moreover, it is one having such a primary particle diameter, and the DBP oil absorption of 30 to 150 ^3/100 g, is preferably used one having a nitrogen adsorption specific surface area of 60~300m ² / g.

  The primary particle size of carbon black affects the adsorptivity of odor components. The primary particle diameter of carbon black is 12 to 40 nm, and if it is less than 12 nm, it is difficult for industrial production. On the other hand, if the primary particle diameter exceeds 40 nm, sufficient storage stability and dispersibility of the coating composition cannot be obtained, and thereby the adsorptivity of odor components is inferior. In addition, a primary particle diameter is measured by well-known methods, such as a microscope method. In the case of ordinary carbon black that is generally used, it is difficult to disperse in the coating composition, and preferably 25 to 40 nm, more preferably 25 to 35 nm. If the primary particle diameter is less than 25 nm, most primary particles form strong aggregates. Since such an aggregate does not dissociate in a solution-like coating composition for forming a hydrophilic coating, the primary particle size is inferior in contamination resistance and odor adsorption by the hydrophilic coating. Is preferably 25 to 40 nm.

  Carbon black is contained at a ratio of (E) / (A + B) of 0.02 to 1, preferably 0.05 to 0.5. If the amount of carbon black is less than 0.02, sufficient contamination resistance cannot be obtained, and odor adsorption is not improved. On the other hand, if the amount of carbon black exceeds 1, carbon black tends to fall off from the film when the film is formed, and no further improvement in contamination resistance and odor adsorption can be expected.

  In the present invention, carbon black can be used as it is. However, the humic acid having at least one selected from a carboxyl group, a hydroxyl group and a salt thereof is attached to the surface of the carbon black in order to disperse the carbon black in the paint. It is preferable from the point. Since humic acids have a variety of functional groups (including carboxyl groups and hydroxyl groups) generated from natural substances and a broad spectrum of molecular weight, they are rich in diversity as surfactants.

  In the present invention, humic acids refer to humic acids, humic acid salts, and salts of these derivatives. That is, humic acid extracted from products obtained by oxidative decomposition of sediments and juvenile charcoal with an oxidizing agent with an aqueous alkaline solution, added with an acidic aqueous solution, precipitated and filtered; this humic acid and alkali metal, ammonium Alternatively, a humic acid salt bonded to a divalent or higher cation; an alkali metal salt of a derivative obtained by polycondensation of the humic acid and an aldehyde, an amine or a phenol; Any one of these humic acids can be used in the present invention, but the humic acids are not limited to these.

  As a method for attaching the humic acids to the carbon black surface, for example, a carbon black powder is sufficiently added to a solution in which humic acids are dissolved or dispersed (water, an aqueous solution, or an organic solvent is used as a solvent). And stirring and mixing to form a suspension to form a suspension, followed by filtration and drying of carbon black. Further, the carbon black suspension can be uniformly dispersed in the hydrophilic film by adding it to the resin composition for forming the hydrophilic film.

  As content of the said humic acids, it is preferable to make it adhere in the quantity of 0.5-100 mass parts with respect to 100 mass parts of carbon black. When the humic acids are less than 0.5 parts by mass, the amount of adhesion to the carbon black is small, the dispersibility of the carbon black at the time of forming the hydrophilic film is not sufficiently satisfied, and when the humic acids exceeds 100 parts by mass, It will degrade the odor adsorption.

Antibacterial and fungicide ingredients
In the present invention, an antibacterial / antifungal agent is added for the purpose of imparting antibacterial / antifungal properties to the resulting heat exchanger. As an antibacterial / antifungal agent used as an active ingredient, it is more preferable to impart either antibacterial or antifungal properties or both. Antibacterial and antifungal agents such as isothiazoline, aldehyde, benzimidazole, halogen, carboxylic acid, sulfamide, thiazole, triazole, phenol, phthalimide, naphthenic acid, pyridine, and the like, Ag Inorganic systems such as Cu, Zn, etc., among which 2,3,5,6-tetrachloro-4-methylsulfonylpyridine, zinc bis [1,2-dihydro-2-thioxopyridine-1- Olato] (zinc polythione) and 2- (4-thiazolyl) -1H-benzimidazole (TBZ) are preferred because they hardly affect the film physical properties such as hydrophilicity, and are excellent in water insolubility and heat stability.

  The antibacterial / antifungal agent has a ratio of (F) / [(A) + (B)] of 0.05 to 1, preferably 0.1 to 0.5. If it is less than 0.05, the content of the antibacterial / antifungal agent is small, and sufficient antibacterial / antifungal properties cannot be obtained. On the other hand, when it exceeds 1, the physical properties of the film such as hydrophilicity are deteriorated.

In addition to the above components, a solvent for dissolving or dispersing is required as a coating composition for solvent- hydrophilized postcoat. Such a solvent is not particularly limited as long as it can dissolve or disperse the above-mentioned components. For example, an aqueous solvent such as water; a ketone system such as acetone, methyl ethyl ketone, methyl iso-butyl ketone, cyclohexanone, and isophorone Solvents; alcohol solvents such as ethanol, isopropanol, n-propanol, n-butanol, iso-butanol, pentanol; ethylene glycol alkyl ether solvents such as ethylene glycol monoethyl ether and ethylene glycol monobutyl ether; diethylene glycol monobutyl ether Diethylene glycol alkyl ether solvents; propylene glycol alkyl ether solvents such as propylene glycol monomethyl ether and propylene glycol monoethyl ether ; And esters of the above series of glycol alkyl ether-based solvents such as ethylene glycol monoethyl ether acetate; include and the like. Among these, an aqueous solvent is preferable and water is particularly preferable.

Other components In the composition of the present invention, if necessary, rust preventives such as tannic acid, gallic acid, phytic acid, and phosphinic acid; leveling agents such as polyalcohol alkyl esters, polyethylene oxide condensate; Fillers such as polyacrylamide and polyvinylacetamide added within a range that does not impair the solubility; Organic pigments such as phthalocyanine compounds; Inorganic pigments such as zinc oxide, silicon oxide (silica), aluminum oxide (alumina), and titanium oxide; alkyl sulfuric acid Surfactants such as ester salts and alkylsulfosuccinates can be added.

  In particular, by adding the above-mentioned inorganic pigments and organic pigments, elution of the pigments can be reduced in a humid atmosphere, and a heat exchanger that does not fade over a long period of time can be obtained.

Formation method for heat exchanger
The coating composition for hydrophilized post-coating of the present invention can be applied to the surface of various substrates, and in particular, is applied to the surface of the substrate formed into the shape of the product by means of molding or the like. It can be suitably used for coating. The substrate to which the coating composition for a hydrophilic postcoat of the present invention is applied is not particularly limited, but is preferably a metal material or an inorganic material. When the base material is an aluminum base material made of aluminum or an aluminum alloy, for example, a rolled material, an extruded shape material, a die-cast material, a cast material, a processed material obtained by appropriately processing these materials, and the like can be given.

When an aluminum substrate is used as the substrate, a solvent-based cleaning agent, an alkaline solution, an acidic solution, a surface active agent is previously applied to the surface of the aluminum substrate before post-coating the hydrophilic post-coating coating composition of the present invention. Pretreatment with a neutral solution containing an agent or the like, or a pretreatment in which two or more of these pretreatments are combined, and even if the surface of the aluminum base material is etched during this pretreatment, it is etched. It does not have to be. In addition, before and after the pretreatment, when two or more kinds of pretreatment are performed, each of the pretreatments may be washed with water, and the water used at this time is industrial water, groundwater, tap water, Either ion exchange water or the like may be used. Furthermore, after pre-treatment or washing with water, drying may be carried out by forced drying means such as air blow, dryer, oven, etc., or by natural drying left at room temperature, if necessary. In addition, for the purpose of imparting corrosion resistance and film adhesion as necessary, a ground treatment such as a known chromate, iron phosphate, zinc phosphate, titanium, zircon, or organic film is applied. Thereafter, the coating composition for hydrophilic post-coating of the present invention is applied by a method such as spraying, dip coating, roll coating, shower coating, etc. and dried to form a film. The dry film amount is suitably about 0.05 to 5 g / m ² . If below 0.05 g / m ^2, not appropriate becomes insufficient hydrophilicity, if greater than 5 g / m ^2, uniform film formation becomes difficult nor economical.

  The present invention will be specifically described with reference to the following invention examples and comparative examples. An aluminum alloy heat exchanger base is immersed in a 30 g / liter aqueous solution of a weak alkaline degreasing agent “Fine Cleaner 315” (trademark, manufactured by Nihon Parkerizing Co., Ltd.) maintained at 60 ° C. for 90 seconds to obtain surface contaminants such as oil. And was washed with tap water for 30 seconds. Next, this was immersed in a 60 g / liter aqueous solution of a phosphate chromate treatment solution “Alsurf 600LN2” (chromate chromate, manufactured by Nippon Paint Co., Ltd.) maintained at 45 ° C. for 60 seconds, washed with tap water for 30 seconds, and then grounded. A treated film was formed. This is pre-processing common to the invention and comparative examples.

  A surface film was formed on the pretreated aluminum alloy heat exchanger substrate by the following method. In addition, all the density | concentrations of the composition in an invention example and a comparative example were shown by the density | concentration display by solid content mass conversion.

The pretreated aluminum alloy heat exchanger substrate was dipped in the following composition for 30 seconds, and then baked and dried in an electric oven maintained at 180 ° C. for 30 minutes to form a surface film.

<Preparation of coating composition for hydrophilized postcoat> Polyacrylic acid (molecular weight (hereinafter abbreviated as Mw)) into an aqueous solution in which 25 parts by mass of polyvinyl alcohol (saponification degree 98%) powder was dissolved in 500 parts by mass of pure water. : 1,000,000) Add 25 parts by mass, stir and disperse forcibly using a disperser, and add 50 parts by mass of an aqueous solution containing 1.0 wt% polyphenol component extracted from oolong tea. 50 parts by mass of an aqueous solution containing 1.0 wt% of a polyphenol component extracted from green tea, Invention Example 3 is 5.0 parts by mass of carbon black A (primary particle size: 28 μm), and Example 4 is a humic acid treatment on the surface. The carbon black B (primary particle size: 28 μm) was 5.0 parts by mass. Inventive example 5 was zinc bis [1,2-dihydro-2-thioxopyridine-1-olate] as an antibacterial and antifungal agent. 10 parts by mass was added, and a predetermined amount of pure water was added thereto to adjust the total amount of the hydrophilic post-coating coating composition to 1000 parts by weight.

  Inventive Examples 6 to 15 adjust the addition amount of polyvinyl alcohol, polyacrylic acid, 1.0 wt% oolong tea polyphenol aqueous solution, 1.0 wt% green tea polyphenol aqueous solution, carbon black B, and antibacterial antifungal agent as described above. Pure water was added to adjust the total amount of the hydrophilic post-coating coating composition to 1000 parts by weight.

Comparative Example A pretreated aluminum alloy heat exchanger was dipped in the composition shown below for 30 seconds and then baked and dried in an electric oven maintained at 145 ° C. for 30 minutes to form a surface film.

Comparative Example 1
<Preparation of coating composition for hydrophilized postcoat> A composition was obtained in which 25 parts by mass of polyacrylic acid (Mw: 1,000,000) was forcibly dispersed in 1000 parts by mass of pure water using a disperser.

Comparative Example 2
<Preparation of coating composition for hydrophilized postcoat> A composition in which polyvinyl alcohol (saponification degree: 98% or more) powder 25 was forcibly dispersed in 1000 parts by mass of pure water using a disperser was obtained.

Comparative Example 3
<Preparation of coating composition for hydrophilized postcoat> 25 parts by mass of polyacrylic acid (Mw: 1,000,000) in an aqueous solution in which 25 parts by mass of vinyl alcohol (saponification degree 98%) powder was dissolved in 500 parts by mass of pure water Was added, stirred and dispersed forcibly using a disperser, and further pure water was added to adjust the total amount of the coating composition for a hydrophilic postcoat to 1000 parts by weight.

Comparative Example 4
<Preparation of coating composition for hydrophilized postcoat> 25 parts by mass of polyacrylic acid (Mw: 1,000,000) in an aqueous solution in which 25 parts by mass of vinyl alcohol (saponification degree 98%) powder was dissolved in 500 parts by mass of pure water Is added and stirred using a disperser to forcibly disperse, 0.8 parts by weight of an aqueous solution containing 1.0 wt% of a polyphenol component extracted from oolong tea is added thereto, pure water is further added, and the hydrophilized post The total amount of the coating composition for coating was adjusted to 1000 parts by weight.

Comparative Example 5
<Preparation of coating composition for hydrophilized postcoat> Polyacrylic acid (Mw: 1,000,000) 2 in an aqueous solution in which 2.5 parts by mass of vinyl alcohol (saponification degree 98%) powder was dissolved in 500 parts by mass of pure water Add 5 parts by mass, stir and use a disperser to forcibly disperse, add 5 parts by mass of an aqueous solution containing 1.0 wt% polyphenol component extracted from oolong tea, add pure water, The total amount of the post-coating coating composition was adjusted to 1000 parts by weight.

Comparative Example 6
<Preparation of coating composition for hydrophilized postcoat> 10 parts by mass of polyacrylic acid (Mw: 1,000,000) in an aqueous solution in which 110 parts by mass of vinyl alcohol (saponification degree 98%) powder was dissolved in 700 parts by mass of pure water Add 50 parts by mass of an aqueous solution containing 1.0 wt% of the polyphenol component extracted from oolong tea, add pure water, and make it hydrophilic for post-coating. The total amount of the coating composition was adjusted to 1000 parts by weight.

Comparative Example 7
<Preparation of coating composition for hydrophilized postcoat> 110 parts by mass of polyacrylic acid (Mw: 1,000,000) in an aqueous solution in which 10 parts by mass of vinyl alcohol (saponification degree 98%) powder was dissolved in 700 parts by mass of pure water Add 50 parts by mass of an aqueous solution containing 1.0 wt% of the polyphenol component extracted from oolong tea, add pure water, and make it hydrophilic for post-coating. The total amount of the coating composition was adjusted to 1000 parts by weight.

These conditions are summarized in Table 1.

<Evaluation Test Method> The heat exchangers produced in Examples 1 to 15 and Comparative Examples 1 to 7 were evaluated by the following methods.

(1) The contact angle of the initial hydrophilic heat exchanger fin part was measured using a contact angle meter.

(2) Hydrophilic durability The contact angle of the fin part immersed in running water for 120 hours at room temperature was measured using a contact angle meter.
◯: The contact angle is 20 ° or less, indicating that it is very good
(Triangle | delta): A contact angle exceeds 20 degrees and is 30 degrees or less, and shows that it is favorable.
X: The contact angle exceeds 30 °, indicating a failure.

(3) A contaminant of palmitic acid was placed in a petri dish at the bottom of a stain-resistant glass container, and a heat exchanger was placed and sealed. The whole glass container was heated to 100 ° C. for 24 hours, and after the sample was exposed to contaminant vapor and contaminated, the contact angle of the heat exchanger fins was measured.

Any of the above (1), (2), and (3) was judged according to the following criteria.
○: Contact angle of less than 20 ° Δ; Contact angle of 20 ° or more and less than 40 ° x; Contact angle of 40 ° or more

(4) Odor Adsorption / Fixability Each heat exchanger was placed in an ammonia atmosphere container, and the ammonia concentration (Ca) in the container after ammonia was adsorbed was measured. Ca is a concentration corresponding to the amount of unadsorbed ammonia. The measurement conditions were as follows. Note that the concentration (Cb) obtained by subtracting the ammonia concentration Ca from the following initial ammonia concentration (15 ppm) is a concentration corresponding to the ammonia adsorption amount by the heat exchanger.
In the table, Cb is shown as odor adsorbability, with ammonia adsorbability. In addition, the criterion was “◯” when Cb was 10 ppm or more, and “X” when Cb was less than 10 ppm.

Heat exchanger size: 100 × 100 × 50 mm ²
Sample container: 5 liter desiccator Gas amount in container: 5 liter Initial gas concentration: Ammonia 15 ppm
Gas measurement method: Ammonia detector tube Laboratory temperature: 20 ° C
Measurement time: 24 hours

  Each heat exchanger adsorbing ammonia was placed in an atmospheric atmosphere container, and the ammonia concentration (Cc) in the container after ammonia was desorbed was measured. The measurement conditions were as follows. The concentration (Cd) obtained by subtracting the ammonia concentration Cc from the ammonia concentration Cb is a concentration corresponding to the ammonia fixing amount by the heat exchanger. Therefore, the ammonia fixing rate (%) is expressed by (Cd / Cb) × 100.

Heat exchanger size: 100 × 100 × 50 mm ²
Sample container: 5 liter desiccator Gas amount in container: 5 liter Initial gas concentration: 0 ppm
Gas measurement method: Ammonia detector tube Laboratory temperature: 20 ° C
Measurement time: 24 hours

  In the table, (Cd / Cb) × 100 is shown as an odor fixing property with an ammonia fixing rate. The determination criteria were “◯” when the fixing rate was 70% or higher, “Δ” when the fixing rate was 50 or higher and lower than 70%, and “X” when the fixing rate was lower than 50%.

(5) Antibacterial and antifungal properties The method was performed according to JIS Z 2911, and the growth of mycelia was examined with the naked eye.
The meanings of the symbols in Table 2, which are the evaluation results, are as follows.
3: Mycelial growth is not observed in the inoculated part of the test piece.
2: The area of the growth part of the mycelium recognized in the inoculated part of the test piece is
Does not exceed 1/3 of the total surface area.
1: The area of the growth part of the mycelium recognized in the inoculated part of the test piece exceeds 1/3 of the total surface area.

  The results are shown in Table 2.

  As can be seen from the results in Table 2, Invention Examples 1 and 2 using acrylic resin, polyvinyl alcohol resin, and oolong tea polyphenol are excellent in hydrophilicity and odor fixability. Furthermore, Invention Examples 3 and 4 containing carbon black are excellent in stain resistance. And the invention examples 5-15 which added the antibacterial agent provided the antibacterial and antifungal property, and were able to provide the outstanding heat exchanger.

  On the other hand, Comparative Example 1 containing no polyacrylic acid was not satisfactory in terms of hydrophilic sustainability and odor fixability. Comparative Example 2 containing no polyvinyl alcohol could not satisfy both initial hydrophilicity and odor fixability. Comparative Examples 3 and 4, which did not contain the oolong tea component and did not reach the predetermined amount, could not satisfy the odor fixability. Comparative Example 5 in which the total amount of polyacrylic acid and polyvinyl alcohol did not reach the predetermined amount could not satisfy the hydrophilicity and the odor fixing property. Comparative Examples 6 and 7, which did not have a blending ratio of polyacrylic acid and polyvinyl alcohol, could not satisfy the hydrophilicity.

Claims (6)

  (A) an acrylic resin, (B) polyvinyl alcohol, (C) a polyphenol component extracted from oolong tea, (D) a solvent, and a hydrophilic coating composition comprising: (A) and (B) The total weight is 1 to 50% by mass with respect to the total amount of the coating composition, the ratio (A) / (B) is 0.1 to 10, and the ratio (C) / (A + B) is 0.00. A coating composition for a hydrophilic postcoat for a heat exchanger, wherein the coating composition is 0005 to 0.5. Furthermore,
(E) Polyphenol component extracted from at least any one of green tea and black tea is contained, The ratio of (E) / (A + B) is 0.0005-0.5, The heat exchange of Claim 1 characterized by the above-mentioned. A coating composition for hydrophilic post-coating for containers. Furthermore,
(F) including carbon black having a primary particle size of 12 to 40 nm,
The ratio of (F) / (A + B) is 0.02-1. The coating composition for hydrophilized postcoat for heat exchangers according to claim 1 or 2.   4. The coating composition for hydrophilicity post-coating for heat exchangers according to claim 3, wherein the surface of carbon black is treated with humic acid. Furthermore,
(G) 2,3,5,6-tetrachloro-4-methylsulfonylpyridine, zinc bis [1,2-dihydro-2-thioxopyridine-1-olate], 2- (4-thiazolyl) -1H- Including at least one of benzimidazole,
The ratio of (G) / [(A) + (B)] is 0.05 to 1. The coating composition for a hydrophilized postcoat for a heat exchanger according to claims 1 to 4.   A heat exchanger produced by painting and baking the composition according to claim 1.